Following the advance of technology, the development of consumer products is progressing as well for meeting the ever-changing requirements of our modern lifestyle. Thus, by the advantages of its flexibility, portability, capability of being rolled up and low cost, flexible electronic products such as flexible display may be the trend of the future. As such products are made from flexible materials; a roll-to-roll (R2R) transporting device is most likely to be adopted in its manufacturing process and is becoming the key device to be improved for perfecting the manufacturing process.
In general, those flexible electronic products, especially the flexible display, are produced by a complex manufacturing process which usually is composed of a plurality of manufacturing procedures. During the operating of such manufacturing process when a substrate of the flexible product is transported from one manufacturing procedure to the next manufacturing procedure, the substrate must be effectively confined for achieving higher accuracy, especially in the stacking and alignment procedures. However, when a roll-to-roll device is adopted in the manufacturing process for transporting the substrate, some form of substrate shifting is inevitable. Therefore, certain guidance system such as a drift corrector should be adopted in the manufacturing process for rectifying the substrate shifting. However, when the drift corrector is applied on a semi-product, i.e. a substrate being processed by a portion of the R2R manufacturing process including wet coating, frame glue coating and medium filling, it is inevitable that the drift corrector will cause the roller to contact with the flexible substrate and thus contaminate the substrate or even cause structural damage on the substrate. As the substrate is transported from one manufacturing procedure to the next manufacturing process for producing the flexible device, any careless handling or pressing during the transportation will cause some sort of damage to the substrate and thus adversely affect the yield of the final product.
In addition, as the flexible substrate is being transported continuously in the manufacturing process, it is usually being processed by a surface processing procedure right after it is being rectified by a drift corrector, and then before the curing of the surface processing, it must be rectified again for preparing the same for the next manufacturing procedure. As such, no matter the rectification is performed by shaking the substrate or enabling the substrate to drift sideways, it is impossible to prevent the roller from contacting with the flexible substrate and thus the production quality of such continuous manufacturing process is adversely affected.
Therefore, for preventing any damage to the flexible substrate during transportation, it is vital for the R2R device to be able to exert a stable confining force upon the thin film substrate for effectively controlling the movement of the same with regard to its transportation, position rectification, tension, and so on. In the conventional R2R manufacturing process, there are several methods being developed for preventing the roller from contacting with the substrate. One of which is executed by recessing the middle portion of the roller for shaping the same similar to a dumbbell. Thereby, when the dumbbell-shaped rollers are used in the R2R device for transporting the substrate, it will only have contact to the substrate by the two bulging ends thereof while preventing the recess portion thereof from contacting with the substrate so that the middle portion of the substrate is not touched by the roller as it is being transported. Another method is performed by forming respectively a plurality of via holes at the two longitudinal sides of the substrate while spacing any two neighboring via holes by a specific interval; and correspondingly, form a plurality of dots on the surface of the roller respectively and linearly at the two ends thereof. Thereby, when the roller is driven to rotate, the dots will inset into their corresponding via holes for driving the substrate to move accordingly and the same time that the moving substrate is confined by the dots inset in the via holes, which is similar to the way how a roll of paper is being rolled and moved in the conventional dot matrix printers.
Except for the aforesaid methods, there is another way for preventing the roller from contacting the substrate, which is a web transporting method and apparatus disclosed in U.S. Pat. No. 6,427,941. In the aforesaid web transporting apparatus, the roller is formed with a plurality of jetting holes on the whole periphery thereof, through which, as the roller is charged with positive air pressure, air is jetted on the web for floating the web in a manner that a smaller air gap is formed between the web and the transporting surface of the roller, and thus the substrate is prevented from contacting directly with the roller. Moreover, different from the aforesaid roller charged with positive pressure, there is another roller using suction for transporting the substrate, as the one disclosed in U.S. Pat. No. 5,931,635. Wherein, the circumferential surface of the roller is covered by a layer consisting of a resilient material. The resilient layer positioned on the circumferential surface of the roller includes a number of suction cups. The roller is designed as a hollow roller which includes a mechanical device by which the suction cups in the resilient layer on the circumferential surface of the roller can be operated by partial deformation of said resilient layer. It is noted that the mechanical device can be two different wheels formed with respective elongate protrusions that are received inside the hollow roller while enabling the protrusions to contact with the interior of the roller intermittently as the wheels are rotating.